This proposed work is designed to elucidate biochemical and physiological mechanisms in the control of food intake involving the ingestion of disproportionate amounts of dietary amino acids or other nutrients in health and disease. Our objective is to determine the location of the critical neural and/or other areas and the mediator, metabolic or otherwise, as well as the mode through which the control mechanism is triggered, in response to the intake of diets containing amino acids or other nutrients in disproportionate quantities. To achieve this goal, we intend to use normal intact or other animals bearing lesions in hypothalamic or extrahypothalamic critical neural areas as well as animals with chronically implanted cannulas centrally or peripherally while being infused with amino acids and other substances, and determine in detail their feeding or dietary choice patterns (including drinking and voluntary running activity patterns, if applicable) using electronic Mettler balances, electronic lick and/or volume detectors as well as electronically monitored activity wheels interfaced with an on-line DPD-11 minicomputer. The change in feeding and other patterns will be closely correlated with changes in biochemical and physiological parameters in blood plasma, brain or other tissues under conditions the food intake controlling mechanism is activated by various experimental dietary treatments especially those containing disproportionate amounts of amino acids, or exogenously introduced substances including amino acids (labeled or unlabeled), other metabolites, drugs, neural humors and others.